Chemistry, microstructure, and electrical properties at interfaces between thin films of titanium and alpha (6H) silicon carbide (0001)

Abstract

Epitaxial thin films (4–1000 Å) of Ti contacts have been deposited via UHV electron beam evaporation at room temperature on monocrystalline, n-type, alpha (6H)-SiC(0001). The interfacial chemistry and microstructure, and the electrical properties, were investigated at room temperature and after annealing at 700 °C up to 60 min. High resolution TEM analyses revealed the formation during annealing of reaction zones consisting of Ti5Si3 and TiC. The corresponding electrical properties exhibited considerable stability except after an initial 20 min anneal. Current-voltage (I-V) measurements showed that the Ti contacts were rectifying with low ideality factors (n < 1.09) and typical leakage currents of 5 × 10−7 A/cm2 at −10 V. The Schottky barrier heights calculated from x-ray photoelectron spectroscopy and I-V and V-V measurements were between 0.79 and 0.88 eV for the as-deposited contacts and between 0.86 and 1.04 eV for the annealed contacts.

Surface morphology and interface structural analyses of Ti(film)/SiC(substrate) by PEEM, SXES, AES and XRD

“…Possible explanations for this broad spectrum are free carbon atoms within the Ti 5 Si 3 -TiC reacted region, the presence of TiC in the amorphous state and/or TiC with dissolved Si atoms. 3,4,15 The spectrum of the sample annealed at 900°C (Fig. 4(c)) resembles that of TiC with the main peak (¾279 eV) and an FWHM of 3.12 eV.…”

“…Figure 4(e), on the other hand, shows the spectrum of TiC with a main peak at ¾278.5 eV (FWHM ¾3.0 eV). Titanium carbide (TiC) is one of the thermodynamically favoured products in the Ti-Si-C system, 3,4 hence the resulting spectra of the annealed samples will be analysed using the spectra of 4H-SiC and TiC. Figure 4(b) shows the C K SXEs spectrum of the sample annealed at 800°C.…”

Correlation between the electrical properties and the interfacial microstructures of TiAl-based ohmic contacts to p-type 4H-SiC

“…9 Extensive investigations have been carried out for development of the ohmic contacts to p-type SiC by the DA technique, and a variety of ohmic contact materials (including mainly titanium or aluminum) have been developed. [10][11][12][13][14][15][16][17][18][19][20][21][22] Among these contact materials, Ti/Al, 5,[10][11][12][13][14][15][16] Ni/Ti/Al, 17,18 and Ge/Ti/Al 19 are expected to satisfy the device designers' requirements (here, a sign "/" between the metals indicates the deposition sequence. ), because their contacts yielded a low specific contact resistance and demonstrated thermal stability.…”

High resolution interface nanochemistry and structure. Progress report, December 1, 1994--November 30, 1995

“…3, ref. 2) indicating local melting may have occurred, whereas all interfaces remain flat in the Ti/SiC case (ref. 4) indicating that a solid state reaction occurred. The difference between these two reaction mechanisms is an important topic for future research as noted below.…”